Contact mechanism



Oct. 30, 1962 C. A. NELSON CONTACT MECHANISM Filed Aug. 19, 1958 1N VENTOR Car/ A. Ne/son ZZJ W a $2 ATTORNEY United States Patent 3,060,675 CONTACT MECHANISM Carl A. Nelson, Lancaster, Pa., assignor to Hamilton Watch Company, Lancaster, Pa., a corporation of Pennsylvania Filed Aug. 19, 1958, Ser. No. 755,973 6 Claims. (Cl. 5828) This invention relates to a contact mechanism for an electric wrist watch and more particularly relates to an improved type of contact mechanism which permits of easy adjustment with tools which are ordinarily available to the average jeweler or watch maker.

The earlier contact mechanisms developed for use in the assignees commercial electric watch, while entirely satisfactory from an operational standpoint, were possessed of the undesirable characteristic of being difiicult to adjust and particularly of being beyond the capabilities of the average jeweler or watch maker. These contacts were initially set in the factory through the use of a special jig and tools and each independent contact sub-assembly was individually tested. The sub-assemblies were later assembled into the finished watches and the watches shipped to jewelers. The contact adjustments were critical and it was found that it was practically impossible to efiiciently and properly adjust the contacts without returning the watch to the factory where the proper tool-s and experience were available.

It is accordingly a primary object of the present invention to provide an improved contact mechanism for a battery operated electric wrist watch which may be removed from the watch and replaced with the ordinary tools of a watch maker.

It is another object of the invention to provide a contact mechanism for a battery operated wrist watch which may be adjusted while utilizing only a pair of jewelers tweezers.

These and further objects and advantages of the invention will become more apparent upon reference to the following specification and claims and the appended drawings wherein:

FIGURE 1 is a partial plan View showing the contact mechanism of the present invention and that portion of a balance wheel necessary to an understanding of the invention; and

FIGURE 2 is a side elevation of the contact mechanism of FIGURE 1.

The contact mechanism is suitable for application to an electric wrist watch of the type shown in assignees US. Patent No. 2,806,908 and the watch is described herein only to the extent necessary to understand the operation of the contact mechanism. Further discussion of the watch itself and the other parts therein may be had by reference to the aforementioned patent.

In the assignees copending application of Philip E. Biemiller et al. Serial No. 551,791, filed December 8, 1955, now Patent No. 2,954,663 there is shown a contact arrangement of a type used in the electric wrist watch shown in the assignees copending application of Philip E. Biemiller et al., Serial No. 578,843, filed April 17, 1956, now Patent No. 2,972,745. The instant contact mechanism is intended for use in the same type of watch and the aforementined copending applications may be referred to for further details of the watch itself.

Referring to the figures of the drawing, a balance staif 10 is shown carrying the cross bar 12 of a balance wheel of the type shown in the aforementioned copending applications. A roller table 14 is secured to the balance staff 10 and oscillates with it. The roller table 14 supports a jewel pin 16 and an arcuate flat contact bar 18. The end of the contact bar 18 is connected to a coil carried by the balance wheel (not shown) and the other end of the contact bar terminates in an upstanding contact 22, all of which is described in further detail in the aforementioned copending applications. The roller table 14 is formed of an insulating mateiral so that the contact bar 18 is insulated from the balance staff 10.

Mounted upon a bridge or plate of the watch assembly is a post 24 carrying the spring contact subassembly. A collet 26 of electrically conducting material is mounted on the post 24, which is also of conducting material but is insulated from the bridge or plate in which it is mounted. This post is connected to one terminal of a battery 28, as is seen in FIGURE 2. The other terminal of the battery 28 is connected to the watch frame work indicated as ground in FIGURE 2.

Mounted in the collet 26 is a reversely bent wire indicated generally at 30 which consists of a substantially straight arm 32, which is hereinafter referred to as the spring arm, and a bent arm 34, hereinafter referred to as the contact arm. As will be seen in the figures of the drawing, the contact arm 34 is looped at 36 intermediate its ends and the spring arm 32 is received between the convolutions of this loop. The formation of the reversely bent wire 30 is such that spring arm 32 engages the convolution of the loop 36 under resilient tension so as to prestress the spring unit.

The bight 38 of the reversely bent spring is threaded through a suitable hole 40 in the collet 26 and is secured therein in a conventional manner by a tapered pin 42. The collet 26 and the post 24 are slotted at 44 and 46 for a purpose presently to become apparent.

When the balance wheel is in the position shown in FIGURE 1, the end 48 of the spring arm 32 engages the upper side of the jewel 16 while a contact 56 on the end of the contact arm 34 engages the upstanding contact 22 on contact bar 18.

As is described in more detail in the aforementioned Patent No. 2,954,663, as the balance wheel oscillates in a counterclockwise direction in FIGURE 1, the jewel pin contacts the end 48 of spring arm 32 prior to any engagement of the contact 50 at the end of contact arm 34 with contact 22. The force which spring arm 32 exerts against jewel 16 is partially determined by the prestressing of the two arms 32 and 34 against one another. That is to say, spring arm 32 resiliently urges loop 36 upward while contact arm 34 urges that loop downward to create a prestressing effect. This prestressing is important in establishing a uniform electrical contact, as is described in the Patent No. 2,954,663.

As the balance wheel rotates further in a counterclockwise direction the contact 50 finally engages contact 22 until engagement between end 48 of spring arm 32 and jewel 16 is terminated. At this time the contact is broken.

The engagement of the end 48 of spring arm 32 with jewel 16 is a critical adjustment which determines the duration of contact and the initial contacting pressure. This adjustment is critical to a few l0-thousandths of an inch and has been difiicult of duplication in the constructions used heretofore.

According to the present invention the critical adjustment of the end 48 of spring arm 32 may be made either by turning the collet 26 on the post 24 or by turning both the collet and post by means of the slots 44 and/ or 46.

The loop 36 serves several different functions. First, this loop serves to position the spring arm and contact arm with respect to one another in a vertical plane. That is to say, as long as the spring arm 32 is within the convolution of the loop 36, it is impossible for the spring arm to move vertically with respect to the contact arm. In addition to this, the loop 36 also serves a second purpose of providing means of adjusting the length of the contact arm 34 and the position of its end 50. The loop may be bent or 3 twisted with tweezers to adjust the position of the end 50 of the contact arm 34 to achieve the desired contact action.

While the fundamentals of operation of this contact system are the same as those disclosed in the previously mentioned Patent No. 2,954,663, the adjustments are considerably simpler and the entire contact sub-assernbly may be removed from the watch by simply removing the collet 26 from the post 24. The contact sub-assembly may later be replaced and the contact adjusted through the simple use of tweezers or a screw driver.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

l. An electric timepiece having an oscillating balance staif; first support means carried by and oscillating with said staif; an insulated pin and a contact carried by said first support means; second support means spaced from said first support means; an elongated spring strip secured intermediate its ends to said second support means and reversely bent to form first and second spring members extending toward said first support means; said first spring member being engageable with said insulated pin and said second spring member with said contact; one of said spring members having a loop intermediate its end and the point at which it is secured to said second support means and the other of said spring members being received within and being guided by the convolution of said loop; and means for closing an electric circuit when said second spring member engages said contact.

2. An electric timepiece as defined in claim 1 wherein said loop is in said first spring member.

3. In an electric timepiece having an oscillating balance wheel and hairspring assembly and including a balance staff; a roller plate carried by said staff; a jewel pin carried by said plate and a contact mounted on said plate; a post mounted in said timepiece; a collet carried by said post; said collet having means to permit adjustment thereof relative to said timepiece; an elongated spring strip secured intermediate its ends to said collet and reversely bent to form two spring members projecting toward said roller plate; one of said spring members being engageable with said jewel pin, and the other spring member being engageable with said contact; said other spring member hav- 4 ing a loop intermediate its end and the point at which it is secured to said collet; and said one spring member being received within and being guided by the convolution of said loop.

4. An electric timepiece having an oscillating balance stait; support means carried by and oscillating with said staff; an insulated pin and a contact carried by said support means; a first elongated spring member secured within said timepiece at a point remote from said support means and engageable with said insulated pin; a second elongated spring member secured within said timepiece at a point remote from said support means and engageable with said contact; said spring members being prestressed so that their unsecured ends are normally biased away from one another; loop-shaped guide means located intermediate the unsupported and supported ends of one of said spring members for maintaining said spring members in substantial parallelism with one another in substantially all directions; and means for closing an electric circuit when said second spring member engages said contact.

5. An electric timepiece as defined in claim 4 wherein said loop-shaped guide means is formed by bending said first spring member intermediate its supported and unsupported ends to form a loop, said second spring member being received within and guided by the convolution of said loop.

6. An electric timepiece having an oscillating balance staff; first support means carried by and oscillating with said stafl; an insulated pin and a contact carried by said first support means; second support means spaced from said first support means; an elongated spring strip secured intermediate its ends to said second support means and reversely bent to form two spring members extending toward said first support means and whose free ends are normally biased away from one another; one of said spring members being engageable with said insulated pin and the other spring member with said contact; loop-shaped guide means located intermediate the free ends of said spring members and the point at which they are secured to said second support means for maintaining said spring members in substantial parallelism with one another in substantially all directions; and means for closing an electric circuit when said other spring member engages said contact.

References Cited in the file of this patent UNITED STATES PATENTS 2,644,293 Black July 7, 1953 2,806,908 Van Horn et a1 Sept. 17, 1957 2,853,849 Beyner Sept. 30, 1958 2,954,663 Biemiller et al. Oct. 4, 1960 

